We have isolated a series of mutant strains of Dictyostelium discoideum in which specific developmentally regulated enzymes are affected. These enzymes, N-acetylglucosaminidase, alpha-mannosidase, beta-glucosidase, and UDPG pyrophosphorylase, accumulate in the wild-type strain more than 10-fold during discrete stages in the developmental sequence. Some of the mutant strains form thermolabide enzyme and thus appear to carry mutations in the structural genes for these enzymes. Other mutations result in the complete loss in enzyme activity. If specific genes are controlled by positive regulatory elements in this eukaryotic organism, we would expect almost equal numbers of mutations in these control elements as are found in the structural genes. By mapping the 50 enzyme specific mutations we have in our collection, we will be able to recognize the genetic complexity of expression of these four genes. We can also determine dominance or recessiveness of putative control genes which can assist in distinguishing regulatory from operator-like elements. This should add considerably to our understanding of genetic control in eukaryotes. To aid in the mapping of the strains we will construct a Tester Strain carrying a recessive growth temperature sensitive allele (ts) and a dominant drug resistance gene. Using this strain we can isolate diploids with our mutant strains without first selecting independent growth temperature sensitive derivatives. We will also select mutations which affect the stage at which a gene is expressed rather than the character of the product. Such mutations will most likely affect control elements and will be genetically and biochemically analyzed. We will determine the various consequences of the these enzymes to biochemical and morphological development. N-acetylglucosaminidase functions during migration; alpha-mannosidase and beta-glucosidase effect macrocyst formation; and UDPG pyrophosphorylase is essential for culmination. We want to further define the steps in those processes in which these enzymes play essential roles.